title: Stimuli-responsive spherical brushes based on D-galactopyranose and 2-(dimethylamino)ethyl methacrylate.
abstract: Stimuli-responsive spherical brushes composed of 6-O-methacryloyl-1,2:3,4-di-O-isopropylidene-D-galactopyranose (MAIGal) and 2-(dimethylamino)ethyl methacrylate (DMAEMA) are prepared via atom transfer radical polymerization (ATRP) using cross-linked polystyrene nanoparticles covered with a thin layer of 2-(2-bromoisobutyryloxy)ethyl methacrylate (BIEM) as ATRP initiator by the "grafting from" approach. The stimuli-responsive behavior of the deprotected spherical PMAGal-b-PDMAEMA block copolymer brushes is investigated by dynamic light scattering and cryogenic transmission electron microscopy. A brush with arms containing 160 MAGal and 170 DMAEMA monomer units shows a significant contraction of the hydrodynamic radius from 20 to 70 °C at pH = 8 with a cloud point at ≈40 °C, whereas no LCST is detected at pH = 6 and 7 due to the protonation of the DMAEMA units. Aggregates occur at low temperatures and pH 8 due to intermolecular interactions between the chains of different brushes, which disappear above LCST, when the PDMAEMA chains fold back to the core of the brushes, exposing the glycopolymer chains to the outside.
authors.affiliation: Makromolekulare Chemie II, Universität Bayreuth, 95440, Bayreuth, Germany; Department of Chemistry, Bülent Ecevit University, 67100, Zonguldak, Turkey.
authors.forename: Hülya
authors.initials: H
authors.lastname: Arslan
authors.forename: André
authors.initials: A
authors.lastname: Pfaff
authors.forename: Yan
authors.initials: Y
authors.lastname: Lu
authors.forename: Petr
authors.initials: P
authors.lastname: Stepanek
authors.forename: Axel H E
authors.initials: AH
authors.lastname: Müller
mesh_terms: D060326:Chemistry Techniques, Synthetic; D003432:Cross-Linking Reagents / Q000737:chemistry; D005690:Galactose / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D008689:Methacrylates / Q000737:chemistry*; D046529:Microscopy, Electron, Transmission / Q000379:methods; D053758:Nanoparticles / Q000737:chemistry*; D011108:Polymers / Q000138:chemical synthesis / Q000737:chemistry*; D011137:Polystyrenes / Q000737:chemistry; D013696:Temperature
chemical_list: D003432:Cross-Linking Reagents; D008689:Methacrylates; D011108:Polymers; D011137:Polystyrenes; C049840:2-(dimethylamino)ethyl methacrylate; D005690:Galactose
keywords: LCST; PDMAEMA; atom transfer radical polymerization (ATRP); glycopolymers; spherical brushes